The famous napkin that linked a young Lionel Messi to Barcelona sold for 762,400 pounds on Friday, British auction house Bonhams said. An agreement in principle to sign the-then-13-year-old Messi was written on the napkin almost 25 years ago at a Barcelona tennis club. Bonhams said the auction was on behalf of Horacio Gaggioli, an agent from Messi’s home country …